The present invention relates to microwave ovens and, more particularly, to a built-in microwave oven, designed to be installed in kitchen furniture at a predetermined position as an integral part of the kitchen furniture and having a cooling structure for forming cooling air currents capable of effectively cooling a variety of heat generating elements within the external casing of the oven.
As well known to those skilled in the art, a microwave oven is an electrically operated oven using high-frequency electromagnetic waves that penetrate food, causing its molecules to vibrate and generating heat within the food to cook it in a short time. Conventional microwave ovens are classified into two types: a tabletop microwave oven designed to be seated on a table and a ventilation hood-combined microwave oven integrated with a gas range at the top portion of the gas range and collaterally acting as a ventilation hood.
In recent years, some kinds of electric kitchen appliances, such as gas oven ranges and pickled vegetable refrigerators, have been designed as built-in types in an effort to accomplish the recent trend of compactness of kitchen systems. Such built-in kitchen appliances preferably accomplish a desired harmony and a desired integration of the electric kitchen appliances with kitchen furniture.
In addition, conventional microwave ovens are typically designed to radiate high-frequency electromagnetic waves from a magnetron into the cooking cavity to allow the electromagnetic waves to penetrate food within the cavity, thus causing molecules of the food to vibrate and generating heat within the food to cook it in a short time. However, such a conventional microwave oven is problematic in that it undesirably has only a single heating mode with high-frequency electromagnetic waves, and so another type of microwave oven having a heater in addition to such a magnetron has been recently proposed and used. That is, microwave ovens, designed to use heat of a heater in addition to high-frequency electromagnetic waves of a magnetron so as to accomplish the requirement for a variety of heating modes and a variety of heating conditions, have been proposed.
The representative example of conventional heaters used in such microwave ovens having heaters in addition to magnetrons is a quartz tube heater. In the microwave oven having such a quartz tube heater as an additional heat source, heat from the quartz tube heater is forcibly convected within the cooking cavity to accomplish a convection-heating effect and to heat food within the cavity to a higher temperature.
Still another type of microwave oven provided with a halogen lamp capable of generating higher temperature heat and browning the surface of food has been proposed and used. In such a microwave oven, halogen lamps are installed at the top and bottom wall of the cavity of the oven, and radiate heat energy and light energy into the cavity, thus heating food within the cavity more quickly. When such halogen lamps are installed in microwave ovens, the lamps generate very high temperature heat, and so it is necessary to additionally install a cooling device for effectively cooling the halogen lamps and the surroundings of the lamps.
In accordance with the recent trend of built-in type structure of kitchen appliances, consumers require built-in microwave ovens. In such built-in microwave ovens, it is desired to install additional heaters, such as halogen lamps, in the ovens so as to accomplish a variety of heating modes and a variety of heating conditions of said ovens.
Such built-in microwave ovens are also set in kitchen furniture as integral parts of the furniture, with only the front walls of the ovens exposed from the front surface of the furniture to allow users to reach said front walls. Therefore, it is necessary to design such built-in microwave ovens to allow air to pass through only the front walls of the ovens.
During an operation of such a built-in microwave oven, the magnetron and the high voltage transformer installed within the machine chamber, in addition to the heater, generates high temperature heat. It is thus necessary to cool the heater and the other heat generating elements installed within the machine chamber of a built-in microwave oven using cooling air current during an operation of the oven.
In such a built-in microwave oven, the air passage for the cooling air has to be provided at the front wall of the oven. However, such an air passage structure for built-in microwave ovens is completely different from that of the other types of conventional microwave ovens, and so it is impossible to use the conventional air passage structures in the built-in microwave ovens.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a built-in microwave oven, which is designed to be installed in kitchen furniture at a predetermined position as an integral part of the kitchen furniture and has a cooling structure for effectively cooling a variety of heat generating elements within the external casing the oven.
In order to accomplish the above object, the present invention provides a built-in microwave oven, comprising: a built-in microwave oven, comprising an external casing, and a cooking cavity set within the external casing and used for heating food seated therein; further comprising: a suction grille provided on the front wall of the external casing at a position corresponding to the upper portion above the cooking cavity for sucking air into the external casing; an exhaust grille provided on the front wall of the external casing for discharging air from the external casing to the atmosphere; a side air passage defined inside the sidewall of the external casing and used for guiding the air from the suction grille to the exhaust grille; a machine chamber air guide passage used for guiding the air from the suction grille to a machine chamber provided within the external casing at a position opposite to the side air passage; an exhaust fan provided within the external casing at a position in back of the suction grille and used for generating a part of the suction force for sucking air into the external casing through the suction grille, and a partition wall installed within the external casing at a position in back of the exhaust fan so as to partition the channel, defined in back of the exhaust fan, into separate air passages, whereby the air sucked into the external casing by the suction force of the exhaust fan partially flows through a rear passage defined in back of the partition wall to a front passage defined in front of the partition wall prior to flowing to the exhaust grille through the side air passage.
In such a microwave oven of this invention, it is possible to allow a sufficient amount of cooling air to smoothly flow through the passages defined by the partition wall, thus effectively cooling a PCB installed within said passages. In addition, it is also possible to form a sufficient amount of cooling air flowing within the external casing of the oven, thus effectively cooling a variety of heat generating elements of the oven during an operation of the oven.